There has been known an image processing apparatus having a plurality of states of power supply which are different in a combination of power supply destinations, and configured to control power supply to respective constitutional elements. For example, there has been known an image processing apparatus which has a power supply-on state and a power supply-off state and which can be switched from the power supply-on state to the power supply-off state on a condition that a power supply-off command is received or non-operating state continues for a predetermined time or longer. The power supply-on state refers to a state where power is supplied to constitutional elements of the apparatus, and the power supply-off state refers to a state where power is supplied to only a constitutional element for receiving a power supply-on command and is not supplied to the other constitutional elements.
For example, JP-A-2009-251275 describes a technique of controlling the power supply. An image forming apparatus described in JP-A-2009-251275 stores a signal from a power supply switch in a non-volatile memory before power supply is interrupted. Then, when the power supply is resumed, the image forming apparatus controls, based on information stored in the non-volatile memory, a return operation in respective cases including a case where normal shutdown processing such as operation of the power supply switch is performed and the power supply is then interrupted, and a case where the power supply is interrupted without performing the normal shutdown processing due to power failure.